Patent GB-1079195-A (GB)
Title: Gas turbine engine cooling
IPC: F02C7/27
Filed: 1966-06-27
Abstract: 1,079,195. Gas turbine engines - starting and cooling. GENERAL MOTORS CORPORATION. June 27, 1966 [July 22, 1965], No. 28613/66. Headings F1G and F1T. A gas turbine engine comprises a starter air chamber having air starter nozzles directed on to the turbine rotor blades, there being openings by which the starter air chamber is connected to the air jacket space of the engine combustion equipment and coolant nozzles connected to the starter air chamber and directed on to the turbine rotor. The invention is described with reference to a gas turbine ducted fan engine which comprises a high pressure turbine 8 and a low pressure turbine 7, Fig. 1 (not shown), the high pressure turbine being shown in Fig. 2 and comprising a rotor 23 carrying blades 25, each blade 25 comprising a root portion 37, a stem portion 39, a platform 42 and a flange portion 43 which defines an opening 49 for inflow of cooling air. A flange portion 45 is secured to the downstream face of the rotor disc and defines an outlet 50 for outflow of cooling air. The turbine inlet nozzle structure comprises a series of hollow vanes 29 mounted at their inner and outer ends in members 28 and 27 respectively, the member 27 defining an annular starting air plenum chamber 57 and starting air nozzles 58 which are arranged to direct starting air on to the rotor blades 25, while the member 28 defines an annular cooling air chamber 66. A plurality of cooling air nozzles 70 is mounted on the wall 67 of the cooling air chamber 66, Fig. 3, whereby cooling air ,may be directed through the opening 49 into the spaces between the blade stems 39 and out through the opening 50. A further series of cooling air nozzles 71 is mounted on the wall 67 Fig. 4, whereby cooling air from the inner air jacket space between the walls 31, 35 of the combustion equipment may also be directed into the spaces between the blade stems 39. At starting of the engine, air under pressure is supplied to the chamber 57 through line 61 and the air discharges through nozzles 58 on to the blades 41 to bring the turbine up to speed. Some air also passes from chamber 57 through the hollow guide vanes 29 to the space 66 and from there some air flows through openings 76 in the flange 32 into the inner air jacket space defined by walls 31, 35 of the combustion equipment thereby acting to cool these parts during starting. A further portion of air from the space 66 passes through the cooling air nozzles 70, Fig. 3, to cool the radially inner ends of the rotor blades 25. When the engine is running, relatively cool air from the inner air jacket space 31, 35 passes through openings 78 to the cooling air nozzles 71, Fig. 4, to cool the radially inner ends of the rotor blades 25, also through openings 76 into the space 66. Some air from the space 66 discharges through nozzles 70 to cool the radially inner ends of the rotor blades 25 while the remaining portion of air from the space 66 flows radially outwardly through the nozzle guide vanes 29 to the chamber 57 thence through the starting air nozzles 58 on to the radially outer ends of the rotor blades 25 for cooling thereof.